Younger age doubles medium-term revision risk after total knee arthroplasty: A nationwide multicenter cohort of 5980 knees from the French SCORE I registry.

Abstract

Although age is a known predictor of outcomes following total knee arthroplasty (TKA), most large-scale studies rely on registry data that lack clinical detail and combines multiple implant designs. This study aimed to determine whether age has an independent effect on implant survivorship and clinical outcomes when a single TKA design is used in a national cohort. A multicenter retrospective cohort analysis was performed using the Amplitude® registry, which prospectively recorded every primary TKA done with the same implant across 15 healthcare facilities between 2002 and 2022. Patients were grouped a priori into three age brackets: <65 years, 65-79 years and >79 years. The primary endpoint was revision-free survival; the secondary endpoints were surgery-free survival, the International Knee Society Score score and knee flexion at one and five years postoperative. Survival analyses were adjusted for sex, body mass index (BMI), American Society of Anesthesiologists (ASA) grade, fixation type and navigation use. Of the 5980 TKAs included, 1276 were in patients <65 years, 3589 in those 65-79 and 1115 in patients >79. The 5-year revision-free survival was 97.5% (<65 years), 98.9% (65-79 years) and 98.7% (>79 years). Compared to the 65-79 year-old group, patients <65 had twice the risk of revision (adjusted hazard ratio [HR] 2.03; 95% confidence interval [CI] 1.20-3.43; p = 0.008), while no difference was found for those >79 (HR 1.14; p = 0.728). Surgery-free survival and complications followed similar trends. No interaction between age and sex, BMI, ASA, fixation or navigation was observed. Functional outcomes improved across all ages; younger patients had higher KSS, but age had no effect on postoperative flexion. Age is an independent predictor of implant survivorship following TKA. While younger patients have good functional outcomes, they remain the Achilles heel of TKA due to their higher risk of revision, whereas patients >79 years of age have comparable implant longevity to 65-79-year-old patients. Level III, retrospective comparative study.